HOT SPOTS   :   

An informal expression designating specific areas as being contaminated with radioactive substances, having a relatively high concentration of air pollutant(s), or experiencing an abnormal disease or death rate.

HUBBLE CONSTANT   :   

The measure of the rate at which the Universe expands is known as the Hubble Constant.

HUMIDITY   :   

The amount of water vapor in the air.

HUMMOCKY   :   

Uneven, lumpy terrain.

HYDRATES   :   

Compounds formed by the union of water with some other substance.

HYDROCARBONS   :   

Chemical compounds containing carbon and hydrogen as the principal elements. Oil is composed primarily of hydrocarbons.

HYDROXYL RADICAL   :   

The neutral form of the hydroxide ion, often referred to as the "detergent" of the troposphere because it reacts with many pollutants, often acting as the first step to their removal.

HYPERPOLARIZATION   :   

The change in a cell's membrane potential, due to the efflux of K+ channels or the influx of Cl- through the Cl- channels, that makes it negative is known as hyperpolarization.

HYPERTEXT   :   

The mark-up language that leads to non-linear transfers of data is known as hypertext. World Wide Web is the most commonly used form of hypertext.

HYPOTHESIS   :   

A testable scientific idea that can be proved right or wrong with experiments. A hypothesis is a formulation of a question that lends itself to a prediction. This prediction can be verified or falsified. A question can only be use as scientific hypothesis, if their is an experimental approach or observational study that can be designed to check the outcome of a prediction.

HYPOXIC   :   

Referring to a condition in which natural waters have a low concentration of dissolved oxygen (about 2 milligrams per liter, compared with a normal level of 5 to 10 milligrams per liter). Most game and commercial species of fish avoid waters that are hypoxic.